Method for the application of an aqueous treatment solution on the surface of a moved steel strip

ABSTRACT

An apparatus and method for the application of an aqueous treatment solution onto the surface of a steel strip that is moved, at a prespecified strip speed, in a direction of movement of the strip, with the following steps: drying of the moving steel strip with a gas flow; application of the aqueous solution on at least one surface of the steel strip with a rotary sprayer with several spray rotors that are situated next to one another, transverse to the direction of movement of the strip, to which the aqueous treatment solution is supplied and which are rotated by a drive, so as to spray the treatment solution, as a result of centrifugal force, in the form of a spray jet, onto the surface of the steel strip and, there, to form a wet film of the aqueous treatment solution; equalization of the applied wet film of the aqueous treatment solution by driven smoothing rollers; and drying of the applied wet film of the aqueous treatment solution.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. §119 to German PatentApplication No. 10 2013 107 505.3 filed 26 Jul. 2013, the entirecontents of which are incorporated herein by reference.

FIELD OF THE DISCLOSURE

The disclosure concerns a method and an apparatus for the application ofan aqueous treatment solution on the surface of a steel strip which ismoved at a prespecified strip speed in the movement direction of thestrip.

BACKGROUND OF THE DISCLOSURE

The treatment of the coated surface of a steel sheet that is coated witha metal anti-corrosion layer after the application of the metal coatingwith an aftertreating agent, so as to make the coated steel sheetresistant to oxidation and to lower the friction coefficient, so thatthe coated steel sheet can be processed better in the subsequentprocessing, for example, during the production of packaging containersis known from the state of the art. From DE 10 2005 045 034 A1, forexample, a method for the passivation of the surface of metal-coatedsteel strips, in particular, tin plate (tinned steel sheets), is known,wherein an aqueous solution of a surface-active substance is sprayed onthe surface of a steel strip that is moved at a strip speed in the rangeof 100 m/min to 600 m/min. The surface-active substance is therebysprayed via at least one tube, which is situated at a distance to thecoated steel strip surface and has at least one borehole, through whichthe aqueous solution of the surface-active substance is sprayed on themetal-coated surface of the steel strip, or on each metal-coatedsurface. After the spraying of the aqueous solution, the excess fractionof the solution is squeezed off the surface by means of squeezingrollers. The wet film of the surface-active substance that remains onthe coated steel strip surface is finally dried, so that a dry, thinfilm of the surface-active substance, with a layer between 2 and 10mg/m², remains on the metal-coated surface of the steel strip.

Another method for the aftertreating agent treatment of a steel strip,in particular, a tin plate strip, which is provided with a metalcoating, is known from DE 10 2012 102 082 B3. In this method, an aqueousaftertreating agent solution is sprayed on the metal-coated surface ofthe steel strip by means of a spraying method. As an alternative for thespraying of the aqueous solution of the aftertreating agent by means ofa spraying method, the application of the aftertreating agent with animmersion method can also be taken into consideration, in which thesteel strip is conducted through a tank that is filled with the liquidaftertreating agent. Both with the known spraying method as well as withthe immersion method, it is necessary to apply the aqueous solution ofthe treatment agent, in excess, on the surface in order to attain ahomogeneous distribution of the treatment agent over the entire surfaceof the steel strip and the removal, again, of the excess fraction of thetreatment solution, for example, with squeezing rollers. Therefore, boththe traditional spraying method as well as the known immersion methodhave the disadvantage that large quantities of the aqueous treatmentsolution are required and that the excess part of the treatmentsolution, which, for example, is squeezed off the surface of the steelstrip by means of squeezing rollers, must be collected in collectingcontainers and conducted to a recycling unit. A recycling of a treatmentsolution, which was already applied once on a metal-coated surface of asteel strip, proves to be, however, cumbersome and expensive, becausethe treatment solution may be contaminated by the application on thesteel strip surface, for example, by metal ions from the metal coatingof the steel strip. Thus, for example, an application of an aqueoustreatment solution on a tin plate surface leads to a contamination ofthe treatment solution with tin ions from the tin coating.

In particular in the known immersion method, there is also frequently anonuniform application of the aqueous treatment solution on the surfaceof the steel strip. This manifests itself, above all, when the steelstrip is moved at a high strip speed of, for example, more than 400m/min through an immersion bath with the treatment solution. Moreover,with the immersion method, there is the problem of an ageing of theaqueous treatment solution which is kept in stock in the immersion bath(tank). In conducting a metal-coated steel strip through an immersionbath, there is also a contamination of the treatment solution, inparticular, due to soiled surfaces of the steel strip and through thedetachment of metal ions from the coating material of the metal coatingof the steel strip. The problem of the ageing of aqueous treatmentsolutions in an immersion bath arises, for example, with chromium-freepassivation agents, which are used for the passivation of tin platesurfaces.

SUMMARY OF THE DISCLOSURE

For this reason, there is a need for a material-sparing method for theapplication of an aqueous treatment solution on the surface of a movedsteel strip, with which a uniform application of the treatment solutionon the steel strip surface is made possible. A goal of embodiments ofthe disclosure, therefore, consists of indicating a method for theapplication of an aqueous treatment solution on the surface of a movedsteel strip, with which, while using the lowest possible quantities ofthe treatment solution, a uniform application of the treatment solutionon the steel strip surface is made possible. Another goal of embodimentsof the disclosure consists in making available a method for theapplication of an aqueous treatment solution on the surface of a movedsteel strip, with which, to avoid ageing effects, the treatment solutioncan be applied, as fresh as possible, after its deposition on the steelstrip surface. It should be thereby possible to also carry out theapplication method at high strip speeds of the moved steel strip.

In the method in accordance with the disclosure, an application of anaqueous treatment solution takes place on the surface of a steel stripthat is moved at a prespecified strip speed in a direction of movementof the strip by application of the aqueous treatment solution on one orboth surfaces of the moved steel strip with a rotary sprayer, which hasseveral spray rotors, located, next to one another, transverse to thedirection of movement of the strip, to which the aqueous treatmentsolution is supplied and which are made to rotate by a drive, so as tospray the aqueous treatment solution, as a result of centrifugal force,in the form of a fine spray jet onto the surface of the steel strip, oronto each surface, and to form, there, a wet film of the aqueoussolution. Before the spraying of the aqueous treatment solution, themoved steel strip is dried and cleaned with a gas flow. After theapplication of the wet film of the aqueous treatment solution, it isevened out on the steel strip surface by means of driven smoothingrollers. The smoothing rollers are thereby appropriately situated,relative to the steel strip surface(s), in such a way that they do notexert any pressure on the wet film of the aqueous treatment solution, oronly a small amount of pressure, and, therefore, do not squeeze off afraction of the applied treatment solution, or only a minimal fraction,from the steel strip surface. After the sprayed wet film has been evenedout, it is dried, so that a dry layer of the treatment substance remainson the treated steel strip surface(s). The dry layer of the treatmentsolution is appropriately between 1 and 50 mg/m² after drying.

The gas flow with which the moved steel strip is cleaned and driedbefore the application of the aqueous treatment solution isappropriately prepared by an Air-Knife and blown, as a laminar hotairflow, onto the surface of the moving steel strip. In this way,disturbing foreign particles are blown off the steel strip surface, andthe steel strip surface is dried.

The quantity of the aqueous treatment solution that is supplied to thespray rotors of the rotary sprayer per unit time is appropriatelyadapted to the strip speed. There is appropriately a linear connectionbetween the quantity of the treatment solution that is supplied to thespray rotors per unit time and the strip speed. The quantity of thetreatment solution that is supplied to the spray rotors per unit timeand related to the width of the steel strip and per side is preferablybetween 0.4 to 5.5 liters per minute and meter is, with particularpreference, in a range between 1 to 3.5 liters per minute and meter,wherein the strip speed is, as a rule, between 200 and 700 m/min. Thelayer of the wet film of the treatment solution that was sprayed withthe spray rotors onto the surface side of the steel strip, or onto eachsurface side, is correspondingly in the preferred range of 2 to 8 mL/m²per side of the steel strip and, preferably, between 4 and 6 mL/m² and,with particular preference, ca. 5 mL/m².

In order to squeeze off as little excess treatment solution as possiblefrom the steel strip surface, the applied wet film of the aqueoussolution is evened out by means of driven smoothing rollers, wherein thesmoothing rollers preferably comprise a pair of smoothing rollers withtwo driven smoothing rollers located, staggered, relative to oneanother. The distance of the smoothing rollers to the steel stripsurface can thereby be appropriately adjusted and adapted to thequantity (layer) of the wet film of the treatment solution that issprayed with the rotary sprayer. Thus, as a function of the sprayedquantity or the layer of the wet film of the treatment solution, it ispossible to attain, on the one hand, an equalization of the applied wetfilm over the entire width of the steel strip, without, on the otherhand, having to squeeze off again excessively large quantities of thesprayed-on wet film from the steel strip surface. As a result, it is nolonger necessary, or it is still necessary only to a very small extent,to again collect excess treatment solution, which is squeezed off ordripped off from the steel strip surface, and to conduct it to apreparation site.

The rotary sprayer is appropriately connected, via a supply line, with asupply container, in which the aqueous treatment solution is kept instock. The aqueous treatment solution can be supplied to the rotarysprayer from the container and, via the supply line, using a pump. Inthe supply container, only fresh treatment solution is, appropriately,kept in stock, so as to avoid ageing problems. In contrast to the knownimmersion method, the treatment solution that is kept in stock in thesupply container does not come into contact with a (perhapsmetal-coated) steel strip before its application on the steel stripsurface, which could lead to a contamination of the fresh treatmentsolution (for example, by detachment of the metal ions from the metalcoating).

The method in accordance with the disclosure is primarily characterizedby its careful resource use of the treatment solution to be applied andby its cost efficiency. In contrast to the known application methods,only the precisely needed quantity of the treatment solution is sprayedonto the steel strip surface, without any excess of treatment solutionhaving to again be blown off or squeezed off. As a result, it is nolonger necessary either to collect excesses of the treatment solutionthat are squeezed off from the steel strip surface or to conduct them toa recycling site. In this way, it is also possible to avoid wastewaterthat has to be treated subsequently and is yielded in recyclingprocesses.

The application method in accordance with the disclosure is suitable forthe application of different treatment solutions onto moved steelstrips. By using the method in accordance with the disclosure, it ispossible, for example, to apply passivation solutions or aftertreatingsolutions onto tin plate surfaces for the reduction of the coefficientvalue. The method in accordance with the disclosure, however, can alsobe used, in an appropriate manner, for the application of other aqueoustreatment solutions on tin plate surfaces or also on the surface ofsteel strips, which are coated with other metal coatings (such as tin-or chromium-containing coatings). The method in accordance with thedisclosure can also be used for the application of aqueous treatmentsolutions on uncoated steel strips, such as, for the application of anaqueous conversion coating on the surface of black plates (hot- orcold-rolled, not descaled, and uncoated steel plates).

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the method in accordance withthe disclosure and the apparatus in accordance with the disclosure canbe deduced from the embodiment example, which is described in moredetail, below, with reference to the accompanying drawings. The drawingsshow the following:

FIG. 1: Schematic representation of an apparatus for the carrying out ofthe method in accordance with the disclosure;

FIG. 2: Detailed view of a section of the apparatus of FIG. 1 in thearea of the rotary sprayer and perspective top view of this rotarysprayer.

DETAILED DESCRIPTION OF THE DISCLOSURE

FIG. 1 schematically shows an apparatus for the carrying out of themethod, in accordance with the disclosure, for the application of anaqueous treatment solution on the surface of a moved steel strip. Thesteel strip 1 is thereby conducted via several deflection rollers U andis moved, at a prespecified strip speed v, in a direction of movement ofthe strip, which is marked, in FIG. 1, with an arrow. The strip speed isthereby, as a rule, more than 200 m/min and up to 750 m/min. The steelstrip 1 can be a cold-rolled steel strip, coated with a metal coating,for example, a tin plate strip or a tinned steel strip. However, it canalso be an uncoated steel plate, such as a black plate strip.

The steel strip 1 is moved by a nondepicted transport device, at aprespecified strip speed v, in a direction of movement of the strip andis thereby conducted with the use of deflection rollers U. First, thesteel strip 1 is conducted by a first drying device 4, so as to dry andclean the surfaces of the steel strip 1. The first drying device 4 isthereby formed, for example, by an “Air-Knife,” which blows a laminarhot airflow onto the surfaces of the steel strip 1, which moves throughat the strip speed v, so as to dry, in this way, the steel stripsurfaces and blow off disturbing foreign particles.

The first drying device 4 is followed by a rotary sprayer 2. The rotarysprayer is shown in detail in FIG. 2. The rotary sprayer 2 has severalspray rotors 3, located, next to one another, transverse to thedirection of movement of the strip, and at a distance to one another.The spray rotors 3 are connected, via a central supply line 6 and branchlines 6 a, 6 b, 6 c, etc., branching off from there, with a supplycontainer 9. The aqueous treatment solution is kept in stock in thesupply container 9; it is to be applied on the steel strip surface. Theaqueous treatment solution is appropriately pumped into the supply line6 by means of a pump 8; from there, it is conducted into the branchlines 6 a, 6 b, 6 c, wherein each branch line is connected with one ofthe spray rotors 3. A throughflow gauge 11 is appropriately provided inthe supply line 6 to record the quantity of the aqueous treatmentsolution that is pumped into the supply line 6.

Via the supply line 6 and the branch lines arranged thereon, the aqueoustreatment solution is supplied to the spray rotors 3 of the rotarysprayer 2. The spray rotors 3 have a plate that is rotated by a drive.As a result of the rotation of the plate of the spray rotors 3, thesupplied aqueous treatment solution is conveyed outward to the edge ofthe plate by centrifugal force. The edge of the plate is shaped in sucha way that the aqueous treatment solution flies off in the form of finedroplets from the edge of the rotating plate. As a function of theviscosity and the surface tension of the treatment solution used, thedroplet diameter lies, as a rule, between 30 and 70 micrometers. Thedroplets of the treatment solution that fly away from the edge of theplate are completely sprayed around the rotating plate of the sprayrotors 3. The spray rotors 3 are arranged transverse to the direction ofmovement of the strip, in such a way, that the spray jets 12 of adjacentspray rotors 3 overlap on the surface of the steel strip 1, so as toprovide a uniform application of the aqueous treatment solution over theentire width B of the steel strip 1.

The quantity of the aqueous treatment solution that is supplied to thespray rotors 3 per unit time is thereby appropriately adapted to thestrip speed v, at which the steel strip 1 is moved. There is thereby alinear relationship between the quantity of the treatment solution thatis supplied to the spray rotors per unit time and the strip speed v. Thequantity M of the treatment solution that is supplied to the sprayrotors per unit time Δt and that is relative to the width B of the steelstrip 1 thereby varies, as a rule, between M/Δt·B=0.4 to 5.5 liters perminute and meter and preferably lies between M/Δt·B=1.0 to 3.5 litersper minute and meter. At a typical strip speed of 200 to 700 m/min, thequantity of the wet film of the treatment solution that is sprayed ontothe surface of the steel strip 1 with the spray rotors 3 is between 2and 8 mL/m² and, preferably, between 4 and 6 mL/m², and, with particularpreference, ca. 5 mL/m².

The aqueous treatment solution can be sprayed, by means of the rotarysprayer 2, either only on one side of the steel strip 1, or also on bothsides of the surfaces of the steel strip 1. Under certain circumstances,rotary sprayers 2 are located, for the purpose, on both sides of thesteel strip 1 that is passed through.

After the application of the aqueous treatment solution as a wet film onthe surface of the steel strip 1, or on each surface, the steel strip 1is passed between smoothing rollers 5 a, 5 b, which are driven in arotating manner. The smoothing rollers 5 serve to equalize the appliedwet film of the aqueous solution. Preferably, a pair of smoothingrollers 5, with two smoothing rollers 5 a and 5 b, which are locatedstaggered with respect to one another, are used for the purpose. Thestaggered arrangement of the smoothing rollers 5 a, 5 b is shown in thefigures. As can be seen from the figures, the smoothing rollers 5 a, 5 bare situated relative to one another, in such a way, that the connectingline of the rotation axes of the smoothing rollers, which run parallelto one another and parallel to the steel strip surface, enclose, in thecross section with the steel strip 1 that is passed through the twosmoothing rollers, an angle of ca. 30° to 60° and, in particular, 45°.In contrast to the squeezing rollers known from the state of the art,which are arranged symmetrical to the steel strip and exert a contactpressure, so as to squeeze off excess treatment solution from the steelstrip surface, the smoothing rollers used here do not exert asubstantial contact pressure on the steel strip surface. Thus, afraction of the sprayed-on treatment solution is not squeezed off, oronly a very small fraction, from the steel strip surface. The smoothingroller pair 5 leads only to an equalization of the wet film of thetreatment solution over the entire surface of the steel strip. Thus, aconstant application of a wet film of the treatment solution, with ahomogeneous layer thickness over the entire surface of the steel strip,is guaranteed, and it prevents excess treatment solution, which wouldhave to be collected and supplied to a recycling unit, from beingyielded.

Following the smoothing rollers 5, the steel strip 1 is conductedthrough a second drying device 7. The second drying device 7 can be adrying furnace or an infrared or hot air drier.

After the drying, a uniform dried layer of the treatment solutionremains on the surface of the steel strip 1, or on each surface, whereinafter the drying, the dried layer is, as a rule, between 1 and 50 mg/m²and, preferably, between 2 and 30 mg/m². With particular preference, thedried layer of the treatment solution is ca. 10 mg/m².

The aqueous treatment solution can be, for example, a chromium-free,surface-active passivation solution, as it was described in DE 10 2005045 034 A1 for the chromium-free passivation of tin plate surfaces. Theaqueous treatment solution can also be a chromium-free passivationsolution for the passivation of tin plate, which contains water-soluble,inorganic compounds of the elements zirconium and titanium or aluminum.Such aqueous treatment solutions can be used in a two-stage passivationmethod for the passivation of tin plate, wherein in a first stage, ananodic oxidation of the tin plate surface is carried out, and in asecond stage, the application of the aqueous treatment solution on thetin plate surface takes place, wherein the treatment solution containswater-soluble, inorganic compounds of the elements zirconium and/ortitanium or aluminum. The application of the aqueous treatment solutioncan thereby take place with the method in accordance with thedisclosure.

The first step of the anodic oxidation of the tin plate surface then hasto also be put first in the application of the aqueous treatmentsolution with the method in accordance with the disclosure. To this end,as shown schematically in FIG. 1, the steel strip 1 is conducted, at theprespecified strip speed v, through a tank 10 with an aqueouselectrolyte (for example, a soda solution) and connected in an electriccircuit as an anode, so as to anodically oxidize the tin plate surface.It has become evident that a particularly inert oxidation layer isformed on the tinned surface of the tin plate by such an anodicoxidation of the tin plate surface; it essentially consists of (inert)tetravalent tin oxide SnO₂, and protects the tin plate surface againstthe natural growth of an oxide layer due to air oxygen or againstreactions with sulfur-containing materials. Such an anodic oxidation ofa tin plate surface, with a subsequent treatment of the oxidized surfacewith a chromium-free, aqueous aftertreating agent, which, in particular,contains titanium and/or zirconium, can therefore comprehensivelyprotect the tinned surface of the steel strip against corrosion andagainst a discoloring of the surface due to a reaction of the tin withsulfur.

With the method in accordance with the disclosure, it is also possibleto apply a metal or organic conversion coating on a black plate(uncoated, cold- or hot-rolled steel plate). It has become evident thatthe method in accordance with the disclosure is suitable, for example,for applying conversion coatings on black plate, which contain metalcomponents, such as titanium, zirconium, manganese, zinc, or alsophosphorus, or organic components, such as polyacrylate orpolycarboxylate. Such conversion coatings offer a good protection to thesurface of the black plate against corrosion, so that black platetreated accordingly, for example, as a replacement for steel plate whichis coated with a metal anti-corrosion layer made of chromium (such asECCS, “electrolytic chromium coated steel”), can be used.

What is claimed is:
 1. Method for the application of an aqueous treatment solution on the surface of a steel strip that is moved, at a prespecified strip speed, in a direction of the movement of the strip, with the following steps: drying of the moving steel strip with a gas flow; application of the aqueous solution on at least one surface of the steel strip with a rotary sprayer with several spray rotors that are situated next to one another, transverse to the direction of movement of the strip, to which the aqueous treatment solution is supplied and which are rotated by a drive, so as to spray the treatment solution, as a result of centrifugal force, in the form of a spray jet, onto the surface of the steel strip and, there, to form a wet film of the aqueous treatment solution; equalization of the applied wet film of the aqueous treatment solution by driven smoothing rollers; drying of the applied wet film of the aqueous treatment solution.
 2. Method according to claim 1, wherein the gas flow is blown onto the surface of the moving steel strip, for the drying of the moving steel band with an Air-Knife, as a laminar hot airflow.
 3. Method according to claim 1, wherein the quantity of the treatment solution that is supplied to the spray rotors per unit time is adapted to the strip speed at which the steel strip is moved.
 4. Method according to claim 3, wherein a linear relationship exists between the quantity of the treatment solution that is supplied to the spray rotors per unit time and the strip speed.
 5. Method according to claim 1, wherein the quantity (M) of the treatment solution that is supplied to the spray rotors per unit time (Δt) and relative to the width (B) of the steel strip lies between M/Δt*B=0.4 to 5.5 liters per minute and meter (l/min*m) and, preferably, between M/Δt*B=1.0 to 3.5 liters per minute and meter (l/min*m).
 6. Method according to claim 1, wherein the strip speed lies between 200 and 700 m/min.
 7. Method according to claim 1, wherein the quantity of the wet film of the treatment solution that is applied with the spray rotors onto the surface side of the steel strip, or onto each surface side, is between 2 mL/m² and 8 mL/m² and, preferably, between 4 mL/m² and 6 mL/m², and, with particular preference, ca. 5 mL/m².
 8. Method according to claim 1, wherein after the drying, the dried layer of the treatment solution lies between 1.0 mg/m² and 50 mg/m², and, preferably, between 2 mg/m² and 30 mg/m², and, with particular preference, ca. 10 mg/m².
 9. Method according to claim 1, wherein the equalization of the applied wet film of the aqueous solution takes place by a driven pair of smoothing rollers with two smoothing rollers that are situated staggered with respect to one another.
 10. Method according to claim 1, wherein the steel strip is a tinned steel strip (tin plate) and that the aqueous treatment solution is a passivation solution for the passivation of the tin coating, in particular, a chromium passivation solution.
 11. Method according to claim 1, wherein the steel strip is an uncoated steel strip (black plate) and that the aqueous treatment solution is a metal-containing or an organic treatment solution for the application of an anti-corrosion conversion coating onto the surface of the steel strip (black plate).
 12. Method according to claim 10, wherein before the application of the aqueous treatment solution, an anodic oxidation of the surface of the steel strip is carried out, which preferably takes place by conducting the steel strip through a basic electrolyte at the strip speed.
 13. Method according to claim 10, wherein the aqueous treatment solution (passivation solution) contains copolymers of acrylate, polymethyl siloxane with polyether side chains, acidic polyether, polymers with heterocyclic groups and/or acidic compositions with complex metal-fluoride anions with divalent or tetravalent cations and polymeric substances.
 14. Method according to claim 1, wherein the aqueous treatment solution contains titanium and/or zirconium or aluminum, in particular, aluminum nitrate.
 15. Method according to claim 11, wherein the aqueous treatment solution contains at least one of the following components: titanium, zirconium, manganese, zinc, phosphorus, polyacrylate, or polycarboxylate.
 16. Apparatus for the carrying out of the method according to claim 1, with: a transport device for transporting the steel strip in a direction of movement of the strip, at a prespecified strip speed; a first drying device for the drying of the steel strip; at least one rotary sprayer with several spray rotors that are situated next to one another, transverse to the direction of movement of the strip, wherein the rotary sprayer for the application of the aqueous treatment solution onto at least one surface of the steel strip is situated at a distance to this surface of the steel strip; a supply device for supplying the rotary sprayer with the treatment solution, with a supply line, which is connected with the rotary sprayer and with a supply container for the aqueous treatment solution; a drive, with which the spray rotors of the rotary sprayer are made to rotate, so as to spray the aqueous treatment solution, as a result of centrifugal force, in the form of a spray jet, onto the surface of the steel strip and, there, to form a wet film of the aqueous solution; a pair of driven smoothing rollers, which are subordinated to the rotary sprayer in the direction of movement of the strip and which are used for the equalization of the applied wet film of the aqueous solution on the surface of the steel strip; a second drying device for the drying of the applied wet film of the aqueous solution.
 17. Apparatus according to claim 16, wherein the supply device comprises a pump, which is connected with a control that is coupled with the transport device, so as to adapt the quantity of the treatment solution that is supplied to the rotary sprayer per unit time to the strip speed. 